Grey Listing outlook/hotmail broken...

This is a problem that we faced 2 years ago.. On big mail services like gmail, hotmail etc it's normal that every message, even from the same sender, comes from a different smtp server, therefore a different IP address.

For this reason, we have created a new option that allows to whitelist sender domains, IP addresses, or CIDRs in the greylist filter. In this case it could be enough to whitelist hotmail.com in the senders list of the greylist filter

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PROBLEM:

We are testing grey listing (default on with protector) and see that mail from hotmail.com will never be delivered. So the greylisting is useless at the moment.

Tested:

Grey Listing Delay (1 minutes)

Grey Listing Autowhitelist (90 days)

The problem is that the retry is coming from a new IP address (not in the database offcoarse L )

Workaround 1:

Use known SPF to make an exeption for Hotmail servers (probably more needed, gmail?

To do this you have to create 39 objects for network ranges. I made mine in 4 network groups named after the SPF records for future maintenance.

spf-a.hotmail.com

spf-b.hotmail.com

spf-c.hotmail.com

spf-d.hotmail.com

Once that's make and exception to skip greylisting for those objects and mail will flow nice and fast if legitimate hotmail mail.